What causes subdural haematomas?

A subdural haematoma occurs when a blood vessel in the space between the skull and the brain (the subdural space) is damaged.

Blood escapes from the blood vessel, leading to the formation of a blood clot (haematoma) that places pressure on the brain and damages it.

Head injuries that cause subdural haematomas are often severe, such as those from a car crash, fall or violent assault. However, minor bumps to the head can also lead to a subdural haematoma in a few cases.

A minor head injury is more likely to lead to a subdural haematoma if you're over 60 years of age, taking blood-thinning medication such as warfarin, or have a history of alcohol misuse.

Outlook

A subdural haematoma is a serious condition that carries a high risk of death, particularly in older people and those whose brain was severely damaged.

Acute subdural haematomas are the most serious type because they're often associated with significant damage to the brain. Those who survive an acute subdural haematoma may take a long time to recover and may be left with physical and mental disabilities.

The outlook is generally better for subacute and chronic haematomas. Most people who are fit enough to have surgery eventually make a full recovery. However, because many people with these types of haematoma are older, they may be too frail to have treatment.